Federal officials have concluded that infrastructure for a proposed hydropower project — which would tap billions of gallons of groundwater in the California desert, just outside Joshua Tree National Park — wouldn’t be especially harmful to the environment. The Bureau of Land Management issued a “finding of no significant impact” Thursday for power lines and water pipelines that would enable Eagle Crest Energy Company to build a massive hydroelectric power plant in the Eagle Mountain area, which is surrounded on three sides by the national park. That finding clears the way for the agency to approve the project infrastructure in a few months, after a final protest period.